Paul Koring

Omar Khadr, then a gravely wounded 15-year-old, was routinely trussed up in a cage “in one of the worst places on Earth,” according to a hulking former military interrogator nicknamed Monster who says he felt sorry for the Canadian and brought him books and treats.

Former specialist Damien Corsetti was testifying via video link to a pretrial hearing in the war-crimes trial of Mr. Khadr, now 23, on charges of terrorism and murder in the killing of a U.S. Special Forces soldier during a firefight in eastern Afghanistan in July of 2002.

“We could do basically anything to scare the prisoners,'' Mr. Corsetti said, adding that detainees were often chained in stress positions in cages and that constant screaming and yelling filled the Bagram prison. He also said beating prisoners was banned but they could be threatened with nightmarish scenarios like clandestine transfer to Israel or Egypt where they would disappear.

Mr. Corsetti was the first defence witness called at the hearing.

“More than anything, he looked beat up,'' Mr. Corsetti said. “He was a 15-year-old kid with three holes in his body, a bunch of shrapnel in his face.'' Bagram guards and interrogators dubbed him Buckshot Bob. Mr. Corsetti said he sometimes took pity on the English-speaking teenager, occasionally chatting with him about fast cars.

He was never one of Mr. Khadr's interrogators.

Mr. Corsetti later faced multiple charges of detainee abuse but was acquitted. He now describes himself as a disabled veteran being treated for post-traumatic-stress disorder.

Defence lawyers are seeking to have Mr. Khadr's confessions at Bagram and Guantanamo kept out of the trial, claiming interrogators coerced them from a tortured and abused child soldier.

The prosecution contends Mr. Khadr was an unlawful combatant who freely and voluntarily confessed to killing Sergeant Christopher Speer with a grenade and boasted of building roadside bombs, being an al-Qaeda fighter and seeking to kill as many Jews and Americans as possible.

Meanwhile, it emerged that information extracted by Canadian spies who interrogated Mr. Khadr in Guantanamo may be used against him, despite Ottawa's belated efforts to have it suppressed.

The Obama administration has rejected Ottawa's request to suppress information that Canadian Security and Intelligence Service agents and Foreign Affairs officials elicited from Mr. Khadr during interrogations in 2003 and 2004.

Nathan Whitling, one of Mr. Khadr's Canadian lawyers who argued his case before Canada's Supreme Court, said the “U.S. refusal of Canada's request confirms its status as an outlaw among the community of nations.''

After the Canadian Supreme Court ruling that successive Canadian governments had failed to safeguard Mr. Khadr's rights, the Harper government – in a formal diplomatic note – pleaded with the Obama administration to block use of the information furnished by the Canadian agents to their U.S. counterparts.

In its written response, the U.S. government declined, saying it was up to the military judge to decide what evidence he allowed.

However, it's not clear from Justice Minister Rob Nicholson's letter whether he believes the Obama administration's changes to the Bush-era military tribunals still operating at Guantanamo makes them legal.

In its ruling, the Supreme Court found the conditions of Mr. Khadr's imprisonment at Guantanamo when he was interrogated by CSIS agents “constituted a clear violation of Canada's international human rights obligations.''